sun planet gear

Ever-Power new planetary reducers hire a floating sun equipment rather than a set position one.
The saying ”There’s nothing new under the sun’ certainly applies to planetary reducers. And, while floating sunlight gears have been around a long time, some engineers may not become aware of the huge benefits this unusual gear design can offer.
Traditionally, planetary reducers possess used a fixed sun gear, where the centre gear is mounted on or machined in to the shaft. When this fixed sun equipment revolves, it turns the earth gears to create movement and/or power. Ever-Power new planetary reducers, however, are having a floating sun equipment rather than a set position sun gear.
Why a floating sunlight gear? ‘In the planetary concept, the sun may be the driver, or pinion, in the gear set,’Ever-Power design engineer Scott sun planet gear Hulstein stated. ‘Because the sun gear is in continuous contact with the planets, it’s important that it is properly centred among the three planets to be able to provide equal load posting among itself and all three planets.’
Due to normal manufacturing tolerances nevertheless, a sun equipment which is securely fixed upon a shaft will intermittently have more load on one planet gear than on another gear Hulstein explained. ‘By permitting the sun equipment to float, it centres itself among the three planets and produces constant, equal load sharing.’
Equal load sharing is merely one of the benefits of this design. The floating sun gear provides ‘true involute actions,’ according to Hulstein. True involute action happens when the rolling motion between the mating gears is really as complete as feasible. The advantage of this comprehensive meshing of gears is certainly longer reducer lifestyle, since less internal equipment slippage means fewer damaged gear teeth.
That also means lower noise amounts. When the sun gear is permitted to completely roll in to the world gears, there’s much less ‘rattling’ as the teeth mesh. In place, the Ever-Power product offers ‘designed out’ the gear mesh sound by allowing sunlight gear to float into place.
So why make use of a set sun gear at all? ‘Fixed sun gears are often used in accurate servo applications,’ Greg Pennings, Ever-Power Consumer Advocate, explained. ‘A set sun gear is necessary when specific positioning and low backlash are an integral part of the software.’ Ever-Power engineers, nevertheless, were less worried about low backlash and more interested with higher torque and/or lower sound applications.
Our planetary reducers with floating sunlight gears were made to compete with parallel shaft reducers, where backlash was less critical,’ Pennings said.
Utilizing the floating sun equipment concept, the Ever-Power planetary reducers can easily exceed the torque ratings of similar sized and larger sized parallel shaft reducers, yet maintain a lesser noise levels.
Sun, Ring and Planet
The most basic type of planetary gearset is shown in the figures above. The figure at left shows a three-dimensional look at as the figure at right provides a cross-section. In this geartrain, inputs and output can be taken from the carrier, band and sunlight gears, and only the planet experiences epicyclic motion. That is the the majority of common type of planetary gearset (apart from the differential) and it finds application in speed reducers and automatic transmissions. If you take apart a cordless drill, you’ll probably find this kind of planetary gearset directly behind the drill chuck.
Two Suns – Two Planets gearset
Cross-sectional view
Two Suns, Two Planets
The gearset proven above has two sunlight gears, and both planet gears (the yellow gears) rotate as an individual unit. The sun gears (green and brown) can rotate independently of one another. The inputs and output can be chosen from either sun equipment and/or the carrier. High speed reductions can be achieved with this unit, but it can suffer from low efficiency if not really designed correctly.
Red sun input – purple sun fixed
Purple sun input – red sun fixed
The animations above show the ‘two suns – two planets’ gearset with one sun as input and the other sun fixed. Note that the carrier rotates clockwise in the animation at still left and counterclockwise in the computer animation at right – despite the fact that the sun rotates counterclockwise in both situations.
The Differential
The gearset shown above differs from the preceding gearsets in that it is made up of miter gears rather than spur (or helical) gears. The ‘sun’ gears are the ones that do not undergo the epicyclic motion experienced by the planet. And the differential can be used to measure the difference in acceleration between two shafts for the intended purpose of synchronization. In addition, the differential is frequently used in auto drive trains to get over the difference in wheel speed when a car goes around a corner.